I follow the Japanese;
Went to college there when I was 21 for a couple semesters. The Japanese eat until they are "90% full," there is some Japanese phrase for this I have long since forgotten. I never eat until full. I am 41 and have a BMI of 18. Are genetics involved...sure. But I just don't eat until full and am not afraid to be hungry. That's my magic diet. Good Luck. YMMV.
RadialGal